On Tue, Oct 13, 2015 at 10:14:03AM +0200, Josef Reidinger wrote:
I'll do more experiments with this as soon as the prototype is easily installable. But looks pretty clear that it would be fairly easy to fix the un-rubism by adding the corresponding methods in the Ruby side in case we decide we are so purist that we cannot live with the current API. :-) So nothing to fix in the libstorage (C++) side.
I agree, that it make sense to have some helpers to have ruby bindings more "ruby".
Just remember that those need documentation and test cases.
a) Is device_graph always an object representing the whole graph?
The devicegraph always represents the whole graph.
Well, in general I do not like this API before and I also do not like it now :) It is not object oriented and whats more device_graph is god like object.
Please elaborate this. What do you mean by God like object? A object that holds all storage objects?
What I expect is object like API that looks like
device_graph.find_device(id)
This exists.
device_graph.find_device("/dev/sda", block: true)
Not type safe.
this way it is more separated responsibility. In general now device_graph looks like target map, which I would like to avoid.
Please explain that, esp. what problems you see with the existing target map and how you still see this problems with the new design.
I prefer to have graph of objects that points to each other
The device-graph is just that and the functions to query the "pointers" exist.
and it is easy to say what object it returns. It also allows easy introspection and better documentation that allows easier usability.
In general your remarks are to buzz-work like to comment on them.
In theory there are many ways to get a subgraph, look at the functions in Device.h.
Storage::Filesystem.find_by_mountpoint(sub_graph, "/")
Do you have a real use-case for that? Adding subgraphs looks like a lot of work so might not be worthwhile.
No concrete example, just wondering. But the idea of restricting the search to a subtree somehow came naturally to my mind while reading. Like "look for a filesystem with this property, but only in this volume group".
Probably not worth the effort, I was just curious.
For bootloader it make sense to e.g. restrict search for boot flag for one disk, as it is disk specific flag.
Then I will look at the subgraph and filtered_graph classes of boost.
Same way it can be interesting to e.g. find intersections for known problem cases like `device_graph.find(fs: "nfs).include?(device_graph.mount_points.get("/boot")`
That's a bad example FMPOV, instead just search for /boot and check whether it is NFS. No need to construct two filtered graphs and check if they intersect.
b) Adding find_by_xx at demand over time doesn't look very future-proof. I would prefer to see something like Rails's #find_by, i.e.
Storage::Filesystem.find(device_graph, mountpoint: "/") Storage::Filesystem.find(device_graph, mountpoint: "/", label: "blah")
Too ruby-centric and not easy to implement in a cross-language way, I guess. But asking does not hurt. :-)
As I already wrote in http://lists.opensuse.org/yast-devel/2014-12/msg00028.html if someone takes care of bindings for a target language more things are possible.
Yes. And it should be fairly easy to implement. But I still wonder about how flexible and future-proof is to keep adding find_by_xx on demand to the API.
I agree, almost all languages have maps that can be used to pass such kind of options. In C it is usually done by flags. In C++ it is usually done by functor. So maybe another option is to have generic find which can take functor or lambda in way like
device_graph.mountpoints.find { |mp| mp.path == "/" || mp.label == "blah" }
A filtered graph constructed by a functor should be possible.
More flexible solutions would also be more complex to use for sure. I just wonder if they are worth exploring. One obvious solution (that would need refinement, of course) if having a search object that accepts any number of key-pair filters. The most primitive form just to expose the idea would be something like (in pseudocode):
s = Storage.search(device_graph, "filesystem") s.add_filter("mountpoint", "/") s.first()
Or any other idea that can be implemented with a fixed set of classes and methods instead of extending the existing classes with new custom methods over time.
Agreed. number for methods for given object should be kept quite low, otherwise it is hard to remember it and also learn it.
In general agreed, but if you have a get_xx and a set_xx function a find_by_xx seems natural.
I think that code is the best documentation if API is small and have good names.
:) ciao Arvin -- Arvin Schnell, <aschnell@suse.com> Senior Software Engineer, Research & Development SUSE Linux GmbH, GF: Felix Imendörffer, Jane Smithard, Graham Norton, HRB 21284 (AG Nürnberg) Maxfeldstraße 5 90409 Nürnberg Germany -- To unsubscribe, e-mail: yast-devel+unsubscribe@opensuse.org To contact the owner, e-mail: yast-devel+owner@opensuse.org